We report the first imported case of African tick bite fever (ATBF) in a patient from Taiwan who returned from a 10-day trip to South Africa. Diagnosis was confirmed by polymerase chain reaction (PCR) from eschar biopsies. Portions of rickettsial ompA (491 bp) and ompB (273 bp) genes were amplified and subsequent sequencing of PCR product showed its 100% identity with R. africae. Microimmunofluorescence (MIF) assay of patient’s serum on Days 14 and 46 after the onset of illness revealed IgG seroconversion when tested with spotted fever group (SFG) rickettsiae antigens, including R. africae. The patient clinically improved on the third day of 14-day treatment with a combination of ciprofloxacin and minocycline. Based on the patient’s travel history and chronology of clinical symptoms, we strongly suspect that the tick-biting event occurred in Kruger National Park.

Successful establishment of a Plasmodium vivax sporozoite challenge model in humans is described. Eighteen healthy adult, malaria-naïve volunteers were randomly allocated to Groups A–C and exposed to 3 ± 1, 6 ± 1, and 9 ± 1 bites of Anopheles albimanus mosquitoes infected with P. vivax, respectively. Seventeen volunteers developed signs and symptoms consistent with malaria, and geometric mean prepatent periods of 11.1 days (9.3–11) for Group A; 10.8 days (9.8–11.9) for Group B; and 10.6 days (8.7–12.4) for Group C, with no statistically significant difference among groups (Kruskal-Wallis, P = 0.70). One volunteer exposed to eight mosquito bites did not develop a parasitemia. No differences in parasite density were observed and all individuals successfully recovered after anti-malarial treatment. None of the volunteers developed parasite relapses within an 18-month follow-up. In conclusion, malaria-naive volunteers can be safely and reproducibly infected with bites of 2–10 An. albimanus mosquitoes carrying P. vivax sporozoites. This challenge method is suitable for vaccine and anti-malarial drug testing.

We evaluated whether sex affects the steady-state pharmacokinetics of the antimalarial drugs, primaquine and doxycycline, in healthy subjects. Seventeen male and 17 female healthy Vietnamese subjects were administered 30 mg (base) of primaquine daily for 14 days. After a 2-week washout period, 14 male and 14 female subjects were administered 100 mg (base) of doxycycline daily for 14 days. Women had significantly higher median values of Cmax (212 versus 122 ng/mL, P< 0.001) and AUC0–24 (1,909 versus 917 ng · h/mL, P < 0.001) of primaquine compared with men. Other than a longer tmax in women, no sex-related differences were seen in the pharmacokinetics of doxycycline. The primaquine pharmacokinetic data suggest that women have increased exposure to primaquine, which may put them at increased risk for toxicity when administered the same maintenance dose as men. The similar pharmacokinetics of doxycycline between the two sexes justifies the same maintenance dose.

Pooling clinical specimens reduces the number of assays needed when screening for infectious diseases. Polymerase chain reaction (PCR)-based assays are the most sensitive tests to diagnose malaria, but its high cost limits its use. We adapted a pooling platform that could reduce the number of assays needed to detect malaria infection. To evaluate this platform, two sets of 100 serum samples, with 1% and 5% malaria prevalence, were tested. DNA, extracted from pooled samples, was amplified by malaria-specific PCR. Additional validation was performed by determining the level of PCR detection based on 1:10 and 1:100 dilution. The platform correctly detected all malaria samples in the two test matrices. The use of stored serum samples also has important implications for studies investigating malaria prevalence rates retrospectively. Field studies, using serum and whole blood specimens, are needed to validate this technique for the adaptation of these methods for clinical utility.

An otherwise healthy 20-year-old woman in Goa, India, received antibiotics after a diagnosis of upper respiratory tract infection. One week later, vivax malaria was diagnosed at a health center, but the patient developed respiratory distress and lost consciousness. She arrived at emergency department in shock, breathless, and comatose. She died within minutes. Two independent laboratories later confirmed Plasmodium vivax by microscopy (140,000/μL) and by nested and real-time polymerase chain reaction methods. Post-mortem examination showed congestion of alveolar capillaries by heavy monocytic infiltrates, along with diffuse damage to alveolar membranes consistent with acute respiratory distress syndrome. Parasites seen in lung tissue were roughly proportionate to both peripheral hyperparasitemia and those seen in other organs without lesions. In this patient, vivax malaria caused a rapidly fatal respiratory distress.

As the goal of malaria elimination from Sri Lanka is currently being pursued, this study was planned to determine the prevalence of asymptomatic malaria infections. Five health areas in Trincomalee and Kurunegala districts that reported high prevalence in the recent past were purposively selected. The smallest administrative units (GN divisions) having high malaria risk within each area were identified. From these divisions, 20% of the population was randomly selected for blood smear examination and in a 50% sub-sample polymerase chain reaction (PCR) assay was performed. A population of 3,730 from 13 GN divisions was sampled. Thick and thin Giemsa-stained blood smears were negative for malaria parasites. The PCR carried out in 50% of the study sample was also negative for malaria parasites. The findings illustrate the absence of asymptomatic carriers in previously high transmission areas and it appears that achieving malaria elimination in Sri Lanka by 2015 is feasible.

Amebiasis remains a major public health issue in most of the world. Amebic liver abscess is the most common extraintestinal manifestation. A complication such as venous obstruction associated with amebiais is rare. We report a thrombosis in hepatic veins associated with amebic hepatic abscess in a traveler.

Using longitudinal data from the Nairobi Urban and Demographic Surveillance System (NUHDSS), we examined the seasonal pattern of pneumonia mortality among under-five children living in Nairobi’s slums. We included 17,787 under-five children resident in the NUHDSS from January 1, 2003 to December 31, 2005 in the analysis. Four hundred thirty-six deaths were observed and cause of death was ascertained by verbal autopsy for 377 of these deaths. Using Poisson regression, we modeled the quarterly mortality risk for pneumonia. The overall person-years (PYs) were 21,804 giving a mortality rate of 20.1 per 1,000 PYs in the study population. Pneumonia was the leading cause of death contributing 25.7% of the total deaths. Pneumonia mortality was highest in the second quarter (risk ratio [RR] = 2.3, confidence interval [CI]: 1.2–4.2 compared with the fourth quarter). The study provides evidence that pneumonia-related mortality among under-fives in Nairobi’s slums is higher from April to June corresponding to the rainy season and the beginning of the cold season.

The objective of this study was to assess the quality of antihypertensive drugs and to investigate the influence of tropical storage conditions. Drug content and in vitro dissolution tests were performed on 10 test formulations (from Rwanda) and 6 reference formulations (from Belgium or France) after purchase and after 6-month storage under long-term (25 ± 2°C and 60 ± 5% relative humidity [RH]) and accelerated (40 ± 2°C and 75 ± 5% RH) testing conditions. Twenty percent of test formulations were of substandard content at the time of purchase. After 6 months at accelerated testing conditions, 7 of 10 test formulations were substandard in content and 8 were substandard for the combined criteria of drug content and dissolution, whereas no reference drug became substandard. This study shows that, apart from some drugs being already substandard from purchase, accelerated testing conditions (simulating tropical climate) have deleterious effects on the majority of antihypertensive drug formulations found in the Rwandan market.

Malaria pigment is an intracellular inclusion body that appears in blood and tissue specimens on microscopic examination and can help in establishing the diagnosis of malaria. In simple light microscopy, it can be difficult to discern from cellular background and artifacts. It has long been known that if polarized light microscopy is used, malaria pigment can be much easier to distinguish. However, this technique is rarely used because of the need for a relatively costly polarization microscope. We describe a simple and economical technique to convert any standard light microscope suitable for examination of malaria films into a polarization microscope.

The harmful effects of female genital mutilation (FGM) on women are recognized worldwide. Although it is practiced by persons of all socioeconomic backgrounds, there are differences within countries and between communities. The aim of this study was to use the 2003 Nigeria Demographic and Health Survey data to determine the spatial distribution of the prevalence of FGM and associated risk factors. Data were available for 7,620 women; 1,673 (22.0%) interviewed had had FGM and 2,168 women had living children, of whom 485 (22.4%) daughters had undergone FGM. Unmarried women were more likely to report a lower prevalence of FGM. Modernization (education and high socioeconomic status) had minimal impact on the likelihood of FGM, but education plays an important role in the mother’s decision not to circumcise her daughter. It follows from these findings that community factors have a large effect on FGM, with individual factors having little effect on the distribution of FGM.

We determined whether the school-based “disease mapping” methodology used to assess urinary schistosomiasis (SCH) is useful for determining trachoma interventions and whether the district-based approach recommended for trachoma is useful for SCH control programs. We conducted two separate integrated surveys in eight districts of central Nigeria: school based and district based. A total of 17,189 children were examined for trachoma and 16,238 children were examined for hematuria from 363 schools and 2,149 households. School surveys identified 67 communities warranting praziquantel drug treatment of SCH and 142 trachoma-endemic communities warranting trachoma control activities. In district-level estimates, we identified 24 communities for praziquantel treatment and 0 for trachoma intervention. Integrating trachoma into SCH school-based surveys, and SCH into trachoma surveys, was quick and easy, but in this setting, school-based surveys were more useful for identifying communities where intervention is warranted.

Schistosomiasis and soil-transmitted helminths (STHs) are most prevalent in developing countries. In Mozambique, the first and only national survey of the distribution and prevalence of schistosomiasis and STHs was conducted in 1952 and 1957. Only occasional surveys in restricted areas have been conducted since the 1950s. The objective of our survey was to update information on the geographic distribution and prevalence of schistosomiasis and STHs in this country. During August 2005–June 2007, the Schistosomiasis and STH Laboratory of National Institutes of Health of the Ministry of Health undertook an epidemiologic survey among schoolchildren. A total of 83,331 persons attending primary schools were sampled. The mean age was 11.36 years (range: 7–22 years). Stool and urine samples were collected and examined by using Kato-Katz and filtration and Ritchie and Willis techniques. Results indicate a widespread occurrence of Schistosoma haematobium (overall prevalence = 47.0%) and STHs (prevalence = 53.5%). Prevalence varied dramatically across the country, with the highest prevalence in districts in northern provinces (Cabo Delgado, Niassa, Nampula, and Zambezia) and in certain provincial capital cities. Districts in the southern region of the country were less affected. Schistosoma mansoni was less common, with prevalence of 1%. We conclude that schistosomiasis and STHs are widely distributed in Mozambique and confirm the need for a national helminth control program.

Particular alleles of the interleukin-1B (IL-1B) gene have been correlated with increased risk of atrophic gastritis and gastric cancer in the populations of East Asia and Europe. No such data exist from Peru, a developing country with a population genotypically different from others studied and with a high prevalence of Helicobacter pylori infection and gastric cancer. We conducted a case-control study comparing 334 hospitalized patients with atrophic gastritis or gastric cancer with 158 nonatrophic gastritis patients (controls). Conditional logistic regression analysis revealed that an increased risk of atrophic gastritis (odds ratio, 5.60) and gastric cancer (odds ratio, 2.36) was associated with the IL-1B-511 C allele. Our study is the first to establish this allele as a risk for these conditions. Given the high prevalence of H. pylori and recurrence rate after treatment, IL-1B-511 single-nucleotide polymorphism analysis may identify those individuals who would benefit most from robust H. pylori eradication efforts in Peru.

To study the distribution and diversity of Bartonella in rodents from Thailand, 330 rodents belonging to 13 species were tested. The majority (80.6%) of rodents examined belonged to the genus Rattus. Bartonellae were cultured from 41.5% of the rodents with a wide range of prevalence by host species and regions. Sequencing of gltA revealed diverse Bartonella strains. Bartonellae from Rattus spp. belonged to 23 variants and clustered with Bartonella coopersplainensis, Bartonella elizabethae, Bartonella phoceensis, Bartonella rattimassiliensis, Bartonella tribocorum, and an unknown geno-group. Bartonellae from Bandicota spp. belonged to six variants and clustered with B. coopersplainensis, B. rattimassilliensis, and B. tribocorum. Three variants from Mus spp. clustered with B. coopersplainensis or B. rattimassilliensis. The only isolate from a Berylmys berdmorei fell into the B. tribocorum group. The observations highlight the need to study these agents for their role in human febrile illnesses of unknown etiology in Thailand and elsewhere in Asia.

The role of the 3′untranslated region (UTR) of the dengue virus (DENV) genome during viral translation remains to be elucidated. We assessed the contribution of well-defined RNA elements in the 3′UTR of DENV-2 to viral translation using a virus-induced reporting gene system and deoxyribozymes (DRzs) targeting the 3′UTR of the DENV-2 genome. Results show that mRNAs carrying a deletion of repeated conserved sequence (RCS2)-CS2 are translated less efficiently than wild type mRNAs. However, mRNAs with a deletion of CS1-stem loop (SL) are translated more efficiently. Thus, CS1-SL and RCS2-CS2 may have different effects on translational regulation. Additionally, the translation-suppressing effect of CS1-SL or the SL element is further confirmed in DENV-2-infected cells using DRzs. Mutagenesis studies show that, rather than the secondary structure, nucleotides 10663–10677 and 10709–10723 are responsible for translational suppression of SL. Overall, our results demonstrate that sequences and elements within the DENV-2 3′UTR regulate viral translation.

Dengue virus (DENV) infection is a worsening global health problem. The plaque reduction neutralization test (PRNT) is currently considered to be the “gold standard” to characterize and quantify circulating levels of anti-DENV neutralizing antibody (NAb). Many variations of the PRNT are currently in use and neither the assay nor its performance conditions have been standardized or harmonized between laboratories. We used a well-characterized panel of acute and late convalescent follow-up sera samples from children experiencing primary and secondary DENV infections to evaluate the performance of the dengue PRNT under a variety of testing conditions. Investigators varied cell type, control virus passage, and the use of complement across multiple assay runs of the same sample panel. Our findings indicate wide variation in PRNT titer results in response to varied testing conditions.

rDEN4Δ30-4995 is a live attenuated dengue virus type 4 (DENV4) vaccine candidate specifically designed as a further attenuated derivative of the rDEN4Δ30 parent virus. In a previous study, 5 of 20 vaccinees who received 105 plaque-forming units (PFU) of rDEN4Δ30 developed a transient elevation of the serum alanine aminotransferase (ALT) level and an asymptomatic maculopapular rash developed in 10 of 20. In the current study, 28 healthy adult volunteers were randomized to receive 105 PFU of rDEN4Δ30-4995 (20) or placebo (8) as a single subcutaneous injection. The vaccine was safe, well-tolerated, and immunogenic. An asymptomatic generalized maculopapular rash and elevations in ALT levels were observed in 10% of the rDEN4Δ30-4995 vaccinees. None of the rDEN4Δ30-4995 vaccinees became viremic, yet 95% developed a four-fold or greater increase in neutralizing antibody titers. Thus, rDEN4Δ30-4995 was demonstrated to be safe, highly attenuated, and immunogenic. However, an asymptomatic localized erythematous rash at the injection site was seen in 17/20 rDEN4Δ30-4995 vaccinees. Therefore, alternative DENV4 vaccine strains were selected for further clinical development.

We assessed the structure and latitudinal selection that might result in sensitivities to critical day-lengths that trigger diapause between Culex pipiens populations distributed along North-South and East-West axes in eastern North America. Strong population structure between Cx. p. pipiens and Cx. p. quinquefasciatus existed. Among Cx. p. pipiens, a 100-km increase in the latitudinal change resulted in an increased square root of FST by 0.002. A 100-km increase in the longitudinal change caused an increased square root of FST by 0.035. A lack of latitudinal influence on the structure between Cx. p. pipiens populations suggests a uniform signal using the 12 microsatellite markers, which might increase the risk of West Nile virus (WNV) transmission toward northern areas because of longer breeding season, extend host-seeking period, and larger population size. Northern Cx. p. pipiens may have undergone additional generations before diapause is triggered, magnifying population size when WNV amplification is peaking.